Coupling a silicon-on-insulator waveguide to a metal–dielectric–metal plasmonic waveguide through a vertical and lateral taper-funnel structure

Abstract

Designing efficient and compact couplers is crucial in hybrid integration of plasmonic components with conventional silicon-on-insulator components. Taper-funnel structures are conventionally used to couple light from a silicon strip waveguide to a metal–dielectric–metal plasmonic waveguide. In this paper, we investigate the effect of different parameters of the metallic funnel and the vertically and laterally tapered silicon waveguide on the performance of the designed coupler. Numerical simulations indicate that the tuned coupler has an average coupling efficiency of 87% in the C-band. The designed 1.18-µm-long coupler has a shorter length compared to the previous designs, while its theoretical coupling efficiency is higher than 85% in the entire O, E, S, C, L, and U bands of optical communication.